Sept 2015 visit to WSU plans We would want to check the effect (ie run control experiments) for poly lysine, since it could act as DNA itself and either being bound to graphene itself, or interfering with DNA binding to graphene. It is often used to get DNA to bind to certain substrates, and it could not do this without first binding to the substrate. Sounds important to understand Mike It would be a great idea. Cornell group used poly-l-lysine and Tris- EDTA (TE) buffer for λ DNA study. We have TE but not sure about poly-l-lysine status. Will check it. Thanks ​What was the solution that the Cornell group used ? Since we have the additional aspect of THz spectroscopy, it would be fine if we to a great extent reproduce their conditions, with the addition of THz spectroscopy Mike Sure Dr. Norton. We have enough DNA crystal buffer components in refrigerator, and I shall prepare the fresh buffer. However I shall add CO buffer in our Check list as well. Thanks Masud It does seem like a good idea to make new buffer solutions since there may be some precipitation or aging that we would not want to ruin our visit. I don't think the complicated buffer :formate dehydrate, 50 mM LiCL and 10% MPD 2-methyl-2-4-pentanediol (from Hampton Research Inc.)​ would be advisable, unless we are going to run controls on the buffer. I would think traditional origami buffer would be sufficient (and we should use it as a blank or control experiment too) Mike I think these DNA solutions are good, especially complimentary and double-stranded ones. We do have micro pipette and tip. And we still have the buffer solution for DNA crystal from several years ago. The buffer component is the buffer is 120 mM magnesium formate dehydrate, 50 mM LiCL and 10% MPD 2-methyl-2-4-pentanediol (from Hampton Research Inc.) We haven't used it for a long time. Maybe we do need new buffer solution. Regards, weidong Hi, We have 13mer ssDNA, Complimentary ssDNA of 13mer and 13mer double-stranded DNA. I will bring higher 100uM stock of these DNA and buffer. Depending on experiment we will dilute them. Do we have to bring micro pipette and tip? Weidong, Do you remember the buffer components of last experiment? Do you have enough buffer or I need to bring some? Thanks Masud Hi all, I will be bringing a myriad of samples for graphene THz modulators. In addition, I have fabricated new GFETs with 5mm^2 detection area for use in DNA detection experiments (as directed by Weidong). If you have request for new (type) of devices, I would be glad to fabricate some. Please let me know. Thanks, Phi Mike I am glad you all come. According to Phi, he will stay for the whole week of sept 14th, so 17th and 18th should be OK. Prof. Brown wants repeat of Graphene-DNA sensing experiments. Although we got very good results, which he will present to Eu-MW2015 next week, we don't understand why the sensitivity of DNA at 101 GHz is lower than we expected. Yes you can bring some of chips Phi sent to you. About DNA, how about 13-mer the same as before but fresh with different concentrations? Or do you have any particular DNA you want to test? We will let you know if we think of anything else. weidong We are making plans for the visit, it looks like David, Masud and Mike can make the trip. Please do confirm that Phi will be there Thursday and Friday (Sept 17th and 18th ) ? Although I have a class thrusday morning, we can leave Huntington at noon and spend the eve of thursday and all of Friday in the visit. I'm sure you have experiments in mind, what do you think we should bring ? Can you describe the type of experiments you would want to perform ? Do you need some of the chips that Phi sent to us, or are you OK for chips ? Particularly what types of DNA would be good for us to bring ? Mike (for David and Masud) Examples of 2 deposition drops above, extent of graphene at blue line. We were covering ~50% of the graphene between the s and d contacts with solutions. Drop did not seem to progress to lower and lower contact angle with time (I think drops with salt/dna behave differently on HOPG). Drops were added as 50uL, allowed, to sit on GFET for 1 minute then blown dry in direction of green arrow. Measurements were all take in ‘dry’ state as seen in middle above. Vgs ramps take about 2 minutes to ramp from 15 Vgs to 35 Vgs. THz radiation is measured in AU, output in volts. GFET DC response is measured in amps with 5-40uA current between source and drain, Ids varying with Vgs. Vds was held at 0.05V for all these measurements. The resistance of gate to source was measured at 60Gohm. attenuator wave guide/horn 101GHz generator with ?? cylinder 101GHz glass sample bed aperture (~1cm) and THz collector Reflector (Al first surface ?) Below is string from just before visit, above is photo of 101GHz transmission setup at Brown lab WSU, gate drain source David The diameter of the aperture is about 1cm matching the area of graphene. About the absolute THz power, I didn't measure it. So you can leave it out of your report. But I will do eventually. Sorry, I reply late. -for all of our recordings on , we used 0.05V source-drain bias -I don't know yet how to explain the quick rise in the THz transmission at the beginning of the measurements after DNA-origami was deposited. -the gate resistance at 30 V is ~60 G ohm. -I didn't measure the incident power hitting on the GFET. The reason is that what matters to us is how much the change will be for the transmitted power if the graphene sheet resistance change. Regards, weidong

101GHz transmission (AU) Ids (amps) X axis is Vgs for all plots. In the pre-water plot, the black X are the ‘settled’ readings; F-8 is 8 minutes prior to final reading, F-11 is 11 minutes before final, etc. The black X pre-water data is shown in all plots for comparison. In other plots water, buffer, etc. the light blue line labeled final is the ‘settled’ reading. All other colors are final reading time minus minutes (e.g. F-8) as multiple ramps were recorded through time as the readings ‘settled’.

Correlate with ‘no dna here’ AFM images With previous GFET

Only 1 or 2 confirmed origami in this scan ‘off drop’ dna drop yes dna drop no

Center GFET between electrodes, on prominent fold. FastscanA – 27um long cantilever (white triangle). Small blue box is approximate location of scans at right – this blue box NOT TO SCALE.

Center of GFET between electrodes, on prominent fold. FastscanA – 27um long cantilever (white triangle). Small white box is approximate location of scans at right (box NOT TO SCALE). Top left and right are same scan at different z-range. Lower left is phase (material sensing) channel which is the clearest depiction of origami immobilized post rinsing. Same area displayed in height channel on bottom right. 100nm

1.5um x 1.5um 0.4um x 0.4um We believe that the scan lines indicated by the blue arrows represent the surface best. This would be described as largely intact dna origami on a bed of disintegrated dna origami. This dna solution was diafiltered <1 hour before expts - final dilution factor is 1:8000 leaving estimated 0.6pM extra co-3970 oligo set (x200 oligonucleotides) Interesting how quickly the probe can change within one image, especially so with this surface and coverage. LOTS OF DNA ON SURFACE BETWEEN SOURCE AND DRAIN EVEN AFTER RINSING